EP0127514B1 - Verfahren und Vorrichtung zur dynamischen Messung von spezifischen Oberflächen und Isothermenbestimmung durch Adsorption und Desorption einer gasförmigen Mischung von konstanter Zusammensetzung - Google Patents

Verfahren und Vorrichtung zur dynamischen Messung von spezifischen Oberflächen und Isothermenbestimmung durch Adsorption und Desorption einer gasförmigen Mischung von konstanter Zusammensetzung Download PDF

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Publication number
EP0127514B1
EP0127514B1 EP84400979A EP84400979A EP0127514B1 EP 0127514 B1 EP0127514 B1 EP 0127514B1 EP 84400979 A EP84400979 A EP 84400979A EP 84400979 A EP84400979 A EP 84400979A EP 0127514 B1 EP0127514 B1 EP 0127514B1
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EP
European Patent Office
Prior art keywords
sample
pressure
katharometer
cell
adsorption
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired
Application number
EP84400979A
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English (en)
French (fr)
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EP0127514A1 (de
Inventor
Pierre Gaston Witier
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Laboratoire Central des Ponts et Chaussees
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Laboratoire Central des Ponts et Chaussees
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Priority to AT84400979T priority Critical patent/ATE29301T1/de
Publication of EP0127514A1 publication Critical patent/EP0127514A1/de
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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N15/00—Investigating characteristics of particles; Investigating permeability, pore-volume or surface-area of porous materials
    • G01N15/08—Investigating permeability, pore-volume, or surface area of porous materials
    • G01N15/088—Investigating volume, surface area, size or distribution of pores; Porosimetry
    • G01N15/0893—Investigating volume, surface area, size or distribution of pores; Porosimetry by measuring weight or volume of sorbed fluid, e.g. B.E.T. method

Definitions

  • the invention relates to the measurement of mass areas and the determination of complete adsorption and desorption isotherms by a dynamic BET type method and apparatus with constant gas mixture composition.
  • the apparatus known from this latter document comprises, from upstream to downstream: a source of a mixture of constant composition of non-adsorbable gas (helium) and adsorbate (nitrogen), followed by a pressure gauge; and two circuits. measurement and reference parallels respectively passing through a catharometer (thermal conductivity detector).
  • the measurement circuit then comprises the sample cell, immersed in a Dewar vessel, a six-way injection valve to calibrate the device, and a flow regulator.
  • the present invention aims to further improve the performance of this type of measurement, in particular the speed and precision.
  • the invention proposes in claim 1 a dynamic BET method according to which, unlike that previously described, the pressure prevailing on the sample is varied between a lower subatmospheric value and higher subatmospheric values or not .
  • the two reference and measurement circuits as indicated in claim 2, flow on a vacuum pump.
  • the apparatus of the invention finds enhanced efficiency when, according to another aspect of the invention, the flow regulator of the measurement circuit is placed upstream of the sample cell, while the total pressure is varied prevailing on the sample by means of a variable pressure drop obtained by a rolling valve (preferably a needle valve) interposed between the cell and the catharometer.
  • a rolling valve preferably a needle valve
  • This diagram shows a source 1 of a gas mixture with a constant composition of an adsorbate, for example nitrogen, and a non-adsorbable gas, for example helium.
  • a regulator 2 is placed behind the source 1.
  • the measurement circuit 3 comprises, a flow regulator 7, a Dewar 5 of liquid nitrogen in which the adsorption cell 6 can be immersed. Downstream of the cell 6, a rolling valve 8 is placed (preferably a needle valve) with a protective filter 9, a conventional six-way gas sampling valve 10, a first ballast 11, the filament catharometer 12, a second ballast 13, and a rotameter 14 for viewing flow.
  • the measurement circuit 3 also includes a branch 15 of the sample cell 6, the branch 15 comprising a needle valve 16 and a rotameter 17.
  • the branch passing through the sample cell also includes a needle valve 18 and a rotameter 19, upstream of the cell, as well as a stop valve 20 downstream.
  • the reference circuit 4 includes a flow regulator 21, the catharometer 12, and a rotameter 22.
  • the two measurement 3 and reference 4 circuits come together to be connected to a vacuum pump 23 via a needle valve 24.
  • Gauges 25, 26, 27 allow the measurement of pressures P o (saturated vapor pressure of nitrogen), P, (total pressure prevailing on the sample), P 2 (pressure in the sampling loop).
  • a supply 28 of helium or nitrogen is connected to the sampling valve 10 using a pressure reducer 29 and a needle valve 30, and allows, in connection with said six-way valve 10, the detector calibration.
  • the main advantage of the assembly of the invention lies, as already noted, in that one can choose a minimum working pressure in the sample cell lower than the pressure atmospheric, and this pressure can be chosen all the lower as the needle valve 8 makes it possible to maintain a very low pressure difference (a few k Pa) between the sample holder and the katharometer circuit.
  • low pressures makes it possible to increase the speed of the heat exchanges by authorizing the use of thin glass cells, for example in the shape of a "U”, easily adaptable to fittings of the "Swagelok” type. These low pressures also increase safety.
  • a second advantageous aspect of the invention consists in that the pressure regulation system (the needle valve 8) introduces a very low dead volume (of the order of cm 3 or less), hence a minimum widening of the peaks adsorption and an increase in the sensitivity, accuracy and speed of the measurement.
  • ballast 11 or the pipes of the circuit of 3 to 4 mm in diameter do not constitute dead volumes in the sense as understood above, that is to say fairly large volumes resulting in a significant widening of the adsorption peak (such as would be caused by a flow regulator or a pressure reducer).
  • Another advantage of the assembly of the invention is that the pressure variation system avoids "jerks" of flow between two successive measurement points (these sudden variations can, on certain devices, project a part of the sample into the pipes).
  • an isotherm of P / can be determined.
  • the measurement of the mass area (P / P o from 0.08 to 0.3) is carried out by varying the pressure P, from 0.015 to 0.075 MPa; a mass area measurement using 4 points of the isotherm can be carried out in 10 to 15 minutes on silica gel (degassing time of the sample excluded).
  • ballast 13 analogous to ballast 11 which makes it possible to delay the passage of a gas of modified composition in the needle valve 24 during the measurements, which would risk causing (small) variations in flow and P 2 .
  • This ballast has the additional function of avoiding, during the establishment of the partial vacuum in the circuit of the catharometer 12, the passage of an excessively large gas flow in the catharometer, which could damage its filaments.

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  • Chemical & Material Sciences (AREA)
  • Biochemistry (AREA)
  • Physics & Mathematics (AREA)
  • Health & Medical Sciences (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Analytical Chemistry (AREA)
  • Dispersion Chemistry (AREA)
  • General Health & Medical Sciences (AREA)
  • General Physics & Mathematics (AREA)
  • Immunology (AREA)
  • Pathology (AREA)
  • Sampling And Sample Adjustment (AREA)
  • Investigating Or Analyzing Non-Biological Materials By The Use Of Chemical Means (AREA)
  • Investigating Or Analysing Materials By Optical Means (AREA)

Claims (7)

1. Verfahren zum Messen spezifischer Oberflächen und zur Bestimmung von Isothermen der Adsorption und vollständiger Desorptionen nach dem dynamischen BET-Verfahren an einer gasförmigen Mischung mit konstanter Zusammensetzung,
dadurch gekennzeichnet, daß der Druck, mit dem die Probe beaufschlagt ist, zwischen einem Wert unterhalb des Atmosphärendrucks und Werten oberhalb des Atmosphärendrucks oder gleich des Atmosphärendrucks variiert wird.
2. Vorrichtung zum Messen spezifischer Oberflächen und zur Bestimmung von Isothermen der Adsorption und vollständiger Desorptionen nach dem dynamischen BET-Verfahren an einer gasförmigen Mischung mit konstanter Zusammensetzung, die in Strömungsrichtung aufweist: eine Quelle (1) der Gasmischung, bestehend aus einem Adsorbat und einem nicht adsorbierbarem Gas, einem Entspannungsventil (2), parallel dazu: einen Bezugskreis (4) und einen Meßkreis (3) mit einer die Probe tragenden Zelle (6), wobei die beiden Kreise (3, 4) ein Katharometer (12) durchqueren,
dadurch gekennzeichnet, daß die beiden Kreise (3, 4) in einer Vakuumpumpe (23) münden.
3. Vorrichtung nach Anspruch 2, gekennzeichnet durch einen Durchflußregler (7), der stromauf zu der die Probe (6) tragenden Zelle angeordnet ist und durch ein Druckverlustregelventil (8), das zwischen der die Probe tragenden Zelle (6) und dem Katharometer (12) angeordnet ist.
4. Vorrichtung nach Anspruch 3,
dadurch gekennzeichnet, daß der Meßkreis (3) eine Drossel (11) aufweist, die stromauf zum Katharometer (12) angeordnet ist.
5. Vorrichtung nach Anspruch 4,
dadurch gekennzeichnet, daß eine Drossel (13) stromab auf das Katharometer folgend angeordnet ist.
6. Vorrichtung nach einem der Ansprüche 3 bis 5,
dadurch gekennzeichnet, daß eine Umgehung der die Probe (6) tragenden Zelle mit einer Durchflußregelung vorgesehen ist.
7. Vorrichtung nach einem der Ansprüche 3 bis 6,
dadurch gekennzeichnet, daß das Regelventil (8) ein Verteilventil ist.
EP84400979A 1983-05-18 1984-05-15 Verfahren und Vorrichtung zur dynamischen Messung von spezifischen Oberflächen und Isothermenbestimmung durch Adsorption und Desorption einer gasförmigen Mischung von konstanter Zusammensetzung Expired EP0127514B1 (de)

Priority Applications (1)

Application Number Priority Date Filing Date Title
AT84400979T ATE29301T1 (de) 1983-05-18 1984-05-15 Verfahren und vorrichtung zur dynamischen messung von spezifischen oberflaechen und isothermenbestimmung durch adsorption und desorption einer gasfoermigen mischung von konstanter zusammensetzung.

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
FR8308242 1983-05-18
FR8308242A FR2546301B1 (fr) 1983-05-18 1983-05-18 Methode et appareil de mesure dynamique des aires massiques (surfaces specifiques) et de determination d'isothermes par adsorption et desorption d'un melange gazeux de composition constante

Publications (2)

Publication Number Publication Date
EP0127514A1 EP0127514A1 (de) 1984-12-05
EP0127514B1 true EP0127514B1 (de) 1987-09-02

Family

ID=9288962

Family Applications (1)

Application Number Title Priority Date Filing Date
EP84400979A Expired EP0127514B1 (de) 1983-05-18 1984-05-15 Verfahren und Vorrichtung zur dynamischen Messung von spezifischen Oberflächen und Isothermenbestimmung durch Adsorption und Desorption einer gasförmigen Mischung von konstanter Zusammensetzung

Country Status (6)

Country Link
US (1) US4528850A (de)
EP (1) EP0127514B1 (de)
AT (1) ATE29301T1 (de)
CA (1) CA1205298A (de)
DE (1) DE3465782D1 (de)
FR (1) FR2546301B1 (de)

Families Citing this family (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE3612817A1 (de) * 1986-04-16 1987-10-22 Alexander Martin Verfahren und vorrichtung zur erstellung von sorptionsisothermen
US4762010A (en) * 1987-04-02 1988-08-09 Mobil Oil Corporation Apparatus and method for adsorption and desorption studies, particularly for characterization of catalysts
US5058442A (en) * 1989-02-15 1991-10-22 Gas Research Institute Apparatus for measuring liquid vapor adsorption and desorption characteristics of a sample
US5342580A (en) * 1990-04-17 1994-08-30 Alan Brenner Apparatus and method for measuring the amount of gas adsorbed on or desorbed from a solid and reactions of a gas with a solid
US5133219A (en) * 1991-02-28 1992-07-28 Micromeritics Instrument Corporation Dynamically balanced, differential gas adsorption appartaus
US10514332B1 (en) * 2016-12-14 2019-12-24 Micromeritics Instrument Corporation Systems and methods for providing a profile of a material property using multiple analysis stations

Family Cites Families (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3211006A (en) * 1961-09-05 1965-10-12 Engelhard Ind Inc Continuous flow method and apparatus for determining adsorption isotherms of solid materials
US3211007A (en) * 1963-03-29 1965-10-12 Cabot Corp Measurement of surface areas of solids
BE720258A (de) * 1967-09-05 1969-02-03
US3555912A (en) * 1969-08-04 1971-01-19 Quantachrome Corp Incremental method for surface area and pore size determination
US3850040A (en) * 1972-08-17 1974-11-26 Micromeritics Instr Corp Sorption analysis apparatus and method

Also Published As

Publication number Publication date
FR2546301A1 (fr) 1984-11-23
DE3465782D1 (en) 1987-10-08
FR2546301B1 (fr) 1985-10-31
EP0127514A1 (de) 1984-12-05
ATE29301T1 (de) 1987-09-15
US4528850A (en) 1985-07-16
CA1205298A (en) 1986-06-03

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